This invention relates to eyeglasses and, more particularly, to vertically adjustable bifocal eyeglasses.
Bifocal lenses for eyeglasses include a lower or reading portion and an upper or long distance portion. A wearer usually looks downwardly through the lower portion when reading or viewing an object close to the eyes and looks straight ahead or upwardly through the upper portion when viewing more distant objects. When the wearer wishes to read something at or above eye level without removing his eyeglasses, he must either tilt his head backwards to an uncomfortable position or raise the eyeglasses frame to permit reading through the lower portions of the lenses.
It is known that this problem can be alleviated by providing the eyeglasses frame with a vertically adjustable nose piece or bridge which is arranged for selectively raising the lenses to a position where the lower portions of the lenses are in a normal line of sight with the object being viewed or the material being read. Prior art arrangements of this type are exemplified in U.S. Pat. Nos. 2,252,922, 2,410,141, 2,486,881, 2,660,924, 3,365,263, 3,552,830, and 4,113,365. The arrangements disclosed in these patents have one or more shortcomings such as vertical adjustment in both directions cannot be conveniently made without at least partically removing the eyeglasses and/or using both hands, asthetically unattractive parts are conspicuous, particulary when the lenses are in a raised position, and the cost of manufacture is relatively high. U.S. Pat. Nos. 1,102,909 and 2,670,658 disclose arrangements which permit vertical adjustment with the frame in place; however, movement of a small catch, knob on the like with one or more fingers is required.